Rough disassembling, breast deboning, thigh deboning processes of chickens, turkeys, etc. have been automatized as automatization in food factories advances in recent years. Especially in the process of deboning a thigh, the step of making incision and deboning has been automatized and thigh meat has been obtained almost without aid of man power by loading a thigh-with-bone to a deboning apparatus except that final step of separation of the thigh meat and oyster meat from the white cap is not yet automatized.
In conventional apparatuses for deboning a thigh, thigh meat is separated from bones together with the oyster meat adhering to the thigh meat, and separation of the oyster meat from the thigh meat is needed to be performed manually.
In the case of a turkey which is a large kind of poultry, a mature cock turkey weighs 18˜20 Kg which is about 10 times of a mature chicken. Turkeys are highly popular in Europe and North America, and production is increasing year by year as health foods, for they are nutritious and low in fat.
By the way, deboning a thigh is carried out manually using a cutter on almost all of the processing lines of turkeys in Europe and the United States. In the case of a cock turkey, deboning a large and heavy turkey thigh, which is about 8 times the weight of a chicken thigh, can be dangerous, as well as demanding lots of time and labor.
In a conventional deboning operation of a chicken thigh, the bones are removed from a thigh-with-bone separated at the femoral joint with the foot part thereof cut away at the spur. About 720 thighs can be deboned on average in a day by a skilled worker. In this case, the worker comes in direct contact with the meat, and the sanitary supervision cost is relatively high. To solve such a problem, a method and a system for deboning edible beasts and birds were proposed in Japanese Laid-Open Patent Application No. 5-184281 (hereafter referred to as patent literature 1).
According to the proposal, as shown in FIG. 6, an incision around the ankle 51 is made, and a longitudinal incision is made to the thigh meat of a work 50 (thigh) at about the same time. Then the shinbone 56 is inserted into the hole of a device (the hole being able to be enlarged elastically) to be drawn through the hole so that the meat is scraped off from the bones in the order of zones E,F and G. During the scraping operation, the sinew 57 is cut with a cutter at the first cutting step 52 and second cutting step 53 to enable the scraping in the F zone. Near the end of deboning 54, a small lump of oyster meat 58 is still connected to the thighbone 55 with the sinew 58a at the white cap 55a at an end of the thighbone with the thigh meat 59 adhering to the oyster meat 58 by the intermediary of a membrane tissue.
FIG. 7(A) is a schematic plan view of the above mentioned deboning apparatus, and FIG. 7(B) is a fragmentary view taken in the direction of the arrows along line VIIB-VIIB of FIG. 7(A). As shown in FIG. 7(A), an octagonal rotary table 61 is provided which can rotate around the main shaft 62 intermittently by 45°. Deboning is carried out at stations S1˜S8, each stations being provided to correspond to eight sides of the table 61. In the drawing, station 8 is depicted with a dotted line because it is positioned under a conveyor 60 described later.
The shinbone of the work 50, which is a thigh to be deboned and transferred on a transfer conveyor 60 to the station 1, is attached to a chuck 67 by human hands, then the thigh meat scraping operation is carried out which consists of drawing the thigh through the device having a flexible hole, making the first and second incisions as shown in FIG. 6 with a pair of cutters 64a, 64b and a single cutter 65 provided at each station so that the thigh meat can be scraped off from the bones in the zones E, F, G sequentially while intermittently rotating the table to feed the work 50 to each station.
The chuck 67 is attached to a lifting rod 68 which can be vertically moved up and down as shown in FIG. 7(B) by an arrow J so that the work 50 attached to the chuck is lifted at stations ST3 and ST6 to scrape off the thigh meat from the bones by means of a meat separator 66.
In FIG. 5 is shown the process of deboning at each station, in which scraping of meat and cutting of sinew are done as follows:
ST1: attaching of thigh,
ST2: making an incision around the ankle,
ST3: scraping of meat from the shinbone and cutting of the sinew of small bones,
ST4: scraping of meat from the shinbone and cutting of the sinew at a joint,
ST5: measuring of position of the joint,
ST6: scraping of meat from a joint part and cutting of the sinew at a joint,
ST7: scraping of meat from a joint part and cutting of the sinew at the thighbone, and
ST8: scraping of meat from the thighbone.
When deboning is completed at ST8, the oyster meat 58 is still adhering to the white cap 55a at an end of the thighbone 55 and the thigh meat 59 is adhering to the oyster meat by the intermediary of a membrane tissue as shown in FIG. 6. Therefore, it is required to automatize the final separation operation to separate the thigh meat and oyster meat from the white cap 55a. 
On the other hand, there is no suitable autoloader available for loading a thigh of an edible beast or bird to said deboning system, and complete automatization had not been realized.
To solve the problem, an auto-loading system was proposed in Japanese Laid-Open Patent Application No. 10-4868, in which a plurality of deboning apparatuses are located along a transfer conveyor for transferring thighs, a plurality of buffer conveyors for allowing temporary retention of works (thighs to be deboned) thereon are provided between the transfer conveyor and the deboning apparatuses respectively so that the work can be fed to the deboning apparatus located downstream without delay and the work transferred by the transfer conveyor can be shifted efficiently from the transfer conveyor to the deboning apparatus and from the same to the transfer conveyor without stopping the transfer of other works by the transfer conveyor.
The construction of the system is, as shown in FIG. 8, composed of a transfer conveyor 70, a plurality of buffer conveyors 80, a plurality of shifting devices 90, a plurality of loading devices 100, a plurality of deboning apparatuses 110, and a controller 111 for controlling the actuation of the shifting devices 90 and loading devices 110. Each of the shifting devices 90 is located to correspond to each of the buffer conveyors 80 and loading devices 100.
The prior art disclosed in patent literature 1 is to automatize deboning operation of a thigh of an edible beast or bird. By the art, the deboning can be performed stably without the need for specialists. Particularly in the case of deboning the thigh of a turkey, by applying the present invention to the turkey processing line in which deboning of the thigh has been carried out manually by skilled workers using cutters, safe deboning operation without a lot of labor becomes possible, however, complete deboning to obtain thigh meat with oyster meat removed can not be realized.